JPS5944602B2 - zoom lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable magnification lens system, or zoom lens, and more particularly to a lens system for use between fixed conjugate planes, for example in a copying machine.

The lens system according to the present invention is disclosed in US Pat. No. 3,844 (19
This is an improvement of the one described in US Pat. No. 3,865,470 (filed September 4, 1973).

One object of the invention is to provide a magnification range of 1: between fixed conjugate planes.
It is an object of the present invention to provide a variable magnification lens system suitable for use in the range of 1.02 to 1:0.615.

Another object of the present invention is to provide a variable magnification lens system that maintains an imaging field of view that is substantially flat regardless of changes in magnification. In the accompanying drawings, a variable magnification lens system, ie, a zoom lens 2, includes the following six lens elements arranged on a single optical axis: a front single lens 4, a tablet 6;
, a single lens 8 , a single lens 10 , a tablet 12 and a rear single lens 14 .

The zoom lens 2 is arranged between two fixed conjugate planes, an object plane 16 and an imaging plane 18.
The front single lens 4 is a convex-concave meniscus lens I, and the tablet 6 is a concave-convex tablet purchased with a biconvex lens and a biconcave lens.

The single lens 8 is a concave-convex meniscus lens, and the single lens 10 is a concave-convex meniscus lens. Further, the tablet 12 is a concave-convex tablet configured with a biconcave lens and a biconvex lens. The rear single lens 14 is a concave-convex meniscus lens. This entire lens system 2 has a conjugate plane 16
, 18, and both the front and rear single lenses 4, 14 and the inner tablet 12 are movable relative to the other lenses. Although an appropriate mechanism is provided to move these lenses, the movement mechanism itself is not the gist of the present application. An important feature of the invention is that the inner tablet 12 is movable with the outer lenses 4,14.

For models that do not have such features and only the outer lens moves, the magnification is low, especially when the magnification is 1:0.65.
In the following cases, the curvature of the imaging field changes rapidly and the quality of the image becomes poor. So the inner tablet 12
By moving the image field, the imaging field can be kept substantially flat regardless of changes in magnification. The parameters of each lens constituting the zoom lens according to the present invention are shown in the table below. , thickness (T) and spacing (S) are given in inches, the minus (d) sign is the radius of the center of curvature on the objective side of the lens, and S1 and S7 are the distances from the objective and imaging plane to their respective adjacent lenses. ).

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a zoom lens system according to the present invention. Figures 2 to 9 are aberration curve diagrams at various magnifications of the lens system according to the present invention, in which the units in the horizontal axis direction are expressed in inches (25.4 degrees), and the wavelength of the incident light ray is is calculated as 453 mm. 1...
...First concave and convex meniscus lens, ...Second tablet convex lens, m...Third tablet concave lens, ...Fourth convex and concave meniscus lens, V...
...5th concave-convex meniscus lens, ...6th
Tablet concave lens, 7th doublet convex lens, 8th concave and convex meniscus lens, 2...
...All lens systems, 6, 12...Tablet, 16...Object plane, 18...Image plane.

Claims (1)

[Claims] 1. A magnification lens system for use between fixed conjugates, comprising: a first convex-concave meniscus lens I; a second double-sided lens II; a third double-concave lens III forming a tablet with the second lens; a fourth convex-concave meniscus lens IV; a fifth concave-concave meniscus lens V; a sixth biconcave lens VI; and the third lens and the fourth and fifth meniscus lenses are fixed to each other as a unit, and the first and eighth meniscus lenses and the sixth and seventh lenses are movable relative to the lens unit. The entire variable magnification lens system is movable between fixed conjugates, and the lens radius (R), thickness (T), and spacing (S
), refractive index (N), and dispersion value (V) are data shown in the table below (in the table, the lens radius, thickness, and spacing are expressed in inches, and the distance between the outermost lenses is and its corresponding conjugate plane), i.e. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ A variable magnification lens system characterized by: